This happens after Valve disputed the significance of the previous Steam 0day disclosed by Kravets on Twitter and banned him out of their HackerOne bug bounty program.

Seeing that this vulnerability impacts only the Steam Windows client, with Steam having over 100 million registered users and 96.28% of them are running Windows according to the Steam Hardware & Software Survey: July 2019, the systems of roughly 96 millions of them are currently affected. "